This invention relates to a current detector for detection or measurement of electric current flowing in an electric circuit, and more specifically to such a detector incorporating a Hall-effect device more generally known also as Hall generator.
The Hall generator is built upon the familiar Hall effect to develop a voltage, known as Hall voltage, in proportion to the strength of the magnetic field applied. Positioned contiguous to a path of electric current, the Hall generator will put out a voltage indicative of the magnitude of the current by being acted upon by the magnetic field appearing in proportion to the current magnitude.
A variety of suggestions have been made with Hall-effect current detectors to cause the magnetic field to act more effectively upon the Hall generator and hence to enhance the sensitivity of current detection. Japanese Unexamined Patent Publication No. 2000-19199 is hereby cited as teaching a current detector bearing particular pertinence to the instant invention. It suggests use of an arcuate current path around the Hall generator. The Hall generator can be subjected to a higher flux density with the arcuate current path than with the more conventional rectilinear current path, producing a higher Hall voltage for a given current magnitude. This prior art device has proved to admit of further improvement for still higher sensitivity.
The present invention aims at drastic enhancement of the sensitivity of the current detector of the kind defined, without making its construction unnecessary complex or expensive.
Briefly, the present invention may be summarized as a current detector utilizing the Hall-effect for detection or measurement of electric current. Included are a first and a second current-path conductor each comprising a pair of terminal webs and a bridge joining the pair of terminal webs. The two current-path conductors are so arranged relative to each other that the bridges thereof are superposed one upon the other with a spacing therebetween. A Hall generator is disposed in the spacing between the bridges of the first and the second current-path conductor so as to be acted upon by magnetic fields that are created upon current flow through the bridges. A coupling conductor interconnects one of the terminal webs of the first current-path conductor and one of the terminal webs of the second current-path conductor, in such a manner that magnetic lines of force due to current flow through the bridges of both current-path conductors act in the same direction on the Hall generator.
Preferably, each current-path conductor is a sheet-metal punching integrally comprising the pair of relatively broad terminal webs which are in side by side arrangement, and the bridge of substantially arcuate shape joining the pair of terminal webs. The arcuate bridge projects laterally of the pair of terminal webs and is constricted to cause concentrated current flow therethrough. The two current-path conductor are arranged in two parallel planes, with at least the bridges thereof superposed one upon the other. Disposed in the spacing between these bridges, the Hall generator is so positioned relative to the bridges as to be thereby surrounded, as seen in a direction normal to the planes of the current-path conductors, in order to be acted upon by magnetic fields that are created upon current flow through the bridges.
Thus, as the magnetic lines of force due to current flow through the bridges of both current-path conductors act in the same direction upon the Hall generator, the latter will be subjected to a flux density approximately twice as high as that to which it would be subjected if, as in the prior art, only one current-path conductor were provided. A material improvement in sensitivity is thus accomplished.
The above and other objects, features and advantages of this invention will become more apparent, and the invention itself will best be understood, from a study of the following description and appended claims, with reference had to the attached drawings showing the preferred embodiments of the invention.